NPS/AR/NRTR-2001/38

Executive Summary

The Red Dog Mine Haul Road traverses 24 miles of
National Park Service (NPS) lands in Cape Krusenstern
National Monument (CAKR), Alaska. Ore trucks use the road to transport 1.1 million dry tons of lead-zinc concentrate annually
from the mine to a port site on the Chukchi Sea. In the summer of 2000, moss
and soil samples were collected from six transects perpendicular to the haul
road in CAKR. Laboratory analyses were performed on the moss Hylocomium
splendens, soil parent material, road dust,
and substrate from materials sites. Analysis revealed a strong road-related
gradient in heavy metal deposition. H. splendens was highly enriched in lead (Pb > 400 mg/kg), zinc (Zn
> 1800 mg/kg), and cadmium (Cd > 12 mg/kg) near the haul road. Concentrations
decreased rapidly with distance from the road, but remained elevated at transect
endpoints 1000 m – 1600 m from the road (Pb >30 mg/kg, Zn >165 mg/kg,
Cd >0.6 mg/kg). Samples collected on the downwind (north) side of the road
had generally higher concentrations of heavy metals than those collected on
the upwind (south) side.

Enrichment factor (EF) analysis of moss versus soil parent
material demonstrates that remobilized soil (e.g., dust composed of roadbed
material) account for only a fraction of the elevated heavy metal concentrations
on the road corridor. Enrichment in Pb, Zn, and Cd from airborne sources other
than remobilized soil (e.g., ore concentrate) is readily apparent. Analysis
of dust shaken from vegetation adjacent to the haul road shows low to average
levels of crustal elements (aluminum and iron) and extremely high levels of
heavy metals. This is especially striking in comparison to materials site samples
that differ in being very low in heavy metals. Considered together, these results
suggest that ore concentrate escapement is occurring along the haul road corridor.
The fact that EF levels remain elevated even at transect endpoints suggests
the additional possibility of contributions of airborne heavy metals from
mining activities to the Omikviorok River drainage as a whole. The source of these
larger scale contributions is unknown and may include the haul road, port site,
mine site, and/or a currently unidentified source.

Results from this study showed Pb levels in excess of 60 mg/kg
dw in all transect points ¡Ü 100 m, with a longer shadow on the downwind (north)
side of the road. In the Nordic moss monitoring program, H. splendens samples in excess of 60-80 mg/kg dw Pb are considered characteristic
of highly polluted areas. Lowest heavy metal concentrations were seen in moss
samples 1000 m – 1600 m from the road on the upwind (south) side. However, even
these samples greatly exceeded maxima seen in previous H.
splendens from arctic Alaska and contained
4-7 times as much Pb, Zn, and Cd as heavily dustladen samples taken adjacent
to the Dalton Highway (Prudhoe Bay Haul Road) in northcentral Alaska. Highest
levels near the Red Dog Haul Road equal or exceed (1.5 – 2.5 times) maxima reported
for samples from severely polluted regions in Central European countries.